1. Field of the Invention
The present general inventive concept relates to a paper feeding apparatus having an improved paper-feeding reliability and an image forming apparatus using the same.
2. Description of the Related Art
Image forming apparatuses form an image on a recording medium. Examples thereof include printers, copy machines, facsimile machines, and all-in-one devices implemented by combining functions of a printer, a copy machine, and a facsimile machine.
Such image forming apparatuses include a paper feeding apparatus for picking up recording media from a cassette sheet by sheet and feeding the recording medium to a printing device.
In the paper feeding apparatus, a knock-up plate for stacking recording media needs to be repeatedly raised and lowered in order to prevent a paper jam between a pickup roller and the knock-up plate that may cause a withdrawal of the cassette and to provide recording media stacked in a plurality of paper feeding units to the pickup roller in an insertion of the cassette.
In addition, a plurality of sheets of paper may be picked up due to static electricity occurring between recording media or a frictional force change between a recording medium and the pickup roller according to a change in a surrounding environment such as temperature and humidity, and accordingly, to prevent the plurality of sheets of paper from being transferred to a printing device, a retard roller is installed to continuously provide a frictional force against a paper transfer direction. It is necessary to release the frictional force provided by the retard roller to a recording medium needs for a correct transfer when the recording medium is transferred to a transfer roller after passing through the pickup roller.
It is also necessary to individually prepare a first driving motor for controlling raising/lowering of the knock-up plate and a second driving motor for controlling raising/lowering of the retard roller. In this case, additional driving axes connected to the first driving motor and the second driving motor, link members, and a control member are used, thereby causing a space limitation and a cost increase in image forming apparatuses that are gradually being miniaturized and light in weight.